System Replacement — Firestone
Heating & AC System Replacement in Firestone, CO
In Firestone, the furnace and AC usually share a birthday: 45.7% of the town was built in the 2000s, and both units went in the same week, from the same builder, off the same spec sheet. They reach the end together, too. This guide covers what a matched furnace + AC system replacement costs in Firestone in 2026, when replacing both beats replacing whichever unit just died, and how to use one planned job to correct the sizing guesses made two decades ago.
Guide by Zach Barbre · Denver HVAC expert
Updated October 2026 · Written from first-hand field experience in the north Denver metro · Prices verified against 2026 Denver-metro quotes
Get a straight answer on your system
Talk to a licensed local installer in Firestone. Free second opinions on replacement quotes — no pressure, no obligation.
Typical response time: under 15 minutes, 7am–7pm daily.
One system or two?
Replace both when the furnace and AC are both 15+ years old — in Firestone, that usually means both are the home's originals. Replace just one when the other unit is under about 10 years old and healthy, and make sure the new unit is matched to it.
- Both units original to a 2000s build — the standard Firestone case in Oak Meadows, St. Vrain Ranch and Neighbors Point: one matched install, one load calculation, one warranty start date.
- One unit failed, the other is the same age — price the matched job before repairing the survivor into a second emergency next season.
- One unit already replaced (say the furnace, in 2022) — replace only the failed unit, and have it matched to the newer equipment.
Call now, don't wait: smell of gas, a carbon monoxide alarm going off, or water pooling under the furnace. Those are same-day problems.
Repair or replace? The honest fork
Repair it
One unit is genuinely young (under 10 years) and the failure is a defined, priced part — capacitor, ignitor, control board. Fix that unit and bank the rest.
Replace it
Both units are 15+ years old, or the dead unit needs a repair over ~$1,500. Two aging systems replaced piecemeal cost more than one planned matched install.
Rule of thumb we stand behind: if the repair costs more than about a third of a new system and the equipment is past 12 years, replacement usually wins on math alone.
What HVAC system replacement costs in Firestone (2026)
Firestone system jobs are usually the clean version of this purchase: two-story homes, modern ductwork built for both seasons, easy basement access. What moves the number is the pairing — a 96% AFUE furnace with a high-SEER2 AC tops the range, a matched standard-efficiency pair sits at the bottom — plus the R-22 question on early-2000s homes, where the original indoor coil retires with the condenser as part of the same scope.
What moves you up or down inside that range:
- Efficiency pairing — A 96% AFUE furnace with a high-SEER2 AC is the top of the range; a matched standard-efficiency pair is the bottom.
- Sizing correction — One Manual J for both seasons replaces the builder's square-foot math from the 2000s; two-story homes feel it most upstairs.
- Refrigerant generation — Early-2000s originals are often R-22 on the cooling side; the matched new coil belongs in this job's scope.
- Ductwork — Young and usually sound in Firestone's stock — a verification item, rarely a project.
Firestone's version of the piecemeal trap has a scheduling twist: because whole subdivisions share equipment birthdays, the emergencies cluster. The same January cold snap that kills your 2007 furnace kills a dozen others on your street, and every Carbon Valley installer is suddenly a week out. The homeowners who plan the matched replacement at the first four-figure repair quote — in October, on their own schedule — pay less and wait less than the ones who buy the identical system during the emergency. Same equipment, different week. It's the same arithmetic in Frederick, a few miles south.
What happens when you call
- We answer and listen. You tell us the symptoms, the equipment's age, and your address. We confirm a licensed installer serves Firestone.
- A licensed local tech arrives. They diagnose, give you repair and replacement options in writing, and answer questions on the spot.
- You contract directly with the installer. The estimate, the work, and the warranty are between you and the licensed company doing the work — not with this guide.
- The installer warranties the work. Equipment warranty from the manufacturer, labor warranty from the installer, both in writing.
How this site works: Mile High HVAC Guide is an independent publisher. We don't install HVAC equipment. When you request help, we connect you with a licensed local contractor and may receive a referral fee from them. It never changes what you pay.
Questions Firestone homeowners actually ask
Should I replace my furnace and AC together?
In Firestone, usually yes — in the 2000s subdivisions both units were installed the same week, so they're the same age and wear out together. One planned install, matched efficiency, one warranty start date, and a lower combined price than two separate jobs. If one unit was already replaced in the last 10 years, replace only the failed one.
How long does a full system replacement take?
Most matched swaps are one long day to two days. Ductwork changes or a venting rework folded into the job push it toward two.
Do I need a permit for this in Firestone?
Yes — a full system replacement in Firestone requires a permit from the Town of Firestone, and the contractor you hire is responsible for pulling it and completing the inspections, which the town handles through SAFEbuilt, its private building inspection partner. A permitted mechanical replacement also triggers Colorado's carbon monoxide rule (C.R.S. § 38-45-102): an operational CO alarm within 15 feet of the entrance to each bedroom. You can verify a permit was issued by calling the town's Planning & Development department at 303-833-3291.
What size system does my house need?
It depends on square footage, insulation, and windows — not on what was there before. A proper installer runs a Manual J load calculation. 'Same size as the old one' without measuring is a red flag.
Get a straight answer on your system
Talk to a licensed local installer in Firestone. Free second opinions on replacement quotes — no pressure, no obligation.
Typical response time: under 15 minutes, 7am–7pm daily.